JSON serialization of ["Hello world !"]

This benchmark must serialize array ["Hello world !"] fastest as possible.
Goal is to benchmark time taken to serialize it without any added code.

Call GET
Response ["Hello World !"] Example

PHP

#1 PHP 7.4 0.4 ms
39,501
#2 PHP 7.2 0.4 ms
37,515
#3 PHP 7.1 0.4 ms
37,359
#4 PHP 7.0 0.5 ms
34,935
#5 PHP 7.3 0.5 ms
34,911

JSON serializers